<template>
  <div class="subject">
    <span>{{num1}}</span>
    <span>+</span>
    <span>{{num2}}</span>
    <span>=</span>
    <input type="number" v-model="result" :disabled="isDis" />
    <button @click="submitFn" :disabled="isDis">提交</button>
  </div>
</template>

<script>
export default {
  props:["index"],
  data () { 
    return {
      num1: Math.floor(Math.random()*(20-0+1)+0),
      num2: Math.floor(Math.random()*(20-0+1)+0),
      result: null,
      isDis: false,  
    }
  },
  methods:{
    submitFn(){
      this.isDis = true;
      let resultStr = ( (this.num1 + this.num2) == this.result ) ? "正确" : "错误";
      this.$emit("result" , resultStr, this.index)
    }
  }
};
</script>

<style scoped> 
.subject {
  margin: 5px;
  padding: 5px;
  font-size: 20px;
}
.subject span {
  display: inline-block;
  text-align: center;
  width: 20px;
}
.subject input {
  width: 50px;
  height: 20px;
}
</style>